Published online Jul 28, 2014. doi: 10.3748/wjg.v20.i28.9626
Revised: January 7, 2014
Accepted: May 23, 2014
Published online: July 28, 2014
Primary malignant melanoma originating in the colon is an extremely rare disease. Herein, we report a case of primary melanoma of the ascending colon. The patient was a 57-year-old male who was admitted to our hospital for persistent abdominal pain and episodes of bloody stool, nausea and vomiting. A computed tomography scan revealed lower intestinal intussusception and enlarged lymph nodes in the abdominal cavity and retroperitoneum. During laparoscopic operation, multiple enlarged lymph nodes were found. Several segments of the proximal small intestine were incarcerated into the distal small intestine, forming an internal hernia and obstruction. The necrotic terminal ileum was invaginated into the ascending cecum. Subsequently, adhesive internal hernia reduction and palliative right hemicolectomy were performed. Pathologic examination of the excised specimen revealed a polypoid mass in the ascending colon. Histological examination showed epithelioid and spindle tumor cells with obvious cytoplasmic melanin deposition. Immunohistochemical staining revealed that the tumor cells were positive for S-100, HMB-45 and vimentin, confirming the diagnosis of melanoma. The patient history and a thorough postoperative investigation excluded the preexistence or coexistence of a primary lesion elsewhere in the skin, anus or oculus or at other sites. Thus, we consider our case to represent an aggressive primary colon melanoma presenting as ileocecal intussusception and intestinal obstruction.
Core tip: Primary malignant melanoma originating in colon is an extremely rare disease. Herein, we report a case of primary colon melanoma causing ileocecal intussusception. A misdiagnosis of intestinal lymphoma, with widespread abdominal lymph nodes metastasis, was made before and during the operation. Immunohistochemical staining confirmed the diagnosis of melanoma.